Five different laboratories participated in an interlaboratory study involving determinations of the iron level in water samples. The results below are replicate determinations of Fe in ppm for laboratories A through E

 

(a) State the appropriate hypotheses.
(b) Do the laboratories differ at the 95% confidence level? At the 99% confidence level (Fcrit = 5.99)? At the 99.9% confidence level (Fcrit = 11.28)?
(c) Which laboratories are different from each other at the 95% confidence level?

Result No. Lab ALab BLab CLab DLab E 10.3 9.5 10.1 8.6 10.6 1 9.9 | 10.0| 9.3 9.6 10.4 9.2 2 11.4 10.5 9.8 11.1 3.